Parent Class for a Energy (CAES) or Thermal Energy Store?

[cavemoa]

Hello,

I'm going to work towards making a CAES simulation using TESPy over the coming months. I have read a number of posts in the Q/A section including the prior answer on CAES. Also the linked paper on CAES application of TESPy and oemof.

So I was going to start by creating a pressure energy/exergy storage component (tank / cavern).

My question is which parent class should I start with? simpleheatexchange?

Looking at the code repository I saw the example in CycleCloser (pump -> pipe = pressure/energy balance). Which made me think pipe might be a good start. Pipe class is based on the simpleheatexchanger (simple.py) of course....

All guidance much appreciated.
Cheers
Jonathan

[fwitte]

Hi Jonathan,

thank you for reaching out. As a very quick feedback to your idea:

I would implement three things:

1. A class that holds a tespy model for charging model and a similar class that holds the model for discharging. They need capabilities to receive input parameters (such as power requirement or pressure + temperature level in the cavern)
2. A class that represents the storage (and does not have anything to do with tespy), in which you can model how the storage behaves with change of mass inside (i.e. pressure + temperature response)
3. Depending on what you want to achieve, e.g. a method/script that couples the plant modeling to the storage modeling per timestep, by orchestrating which of the models are called in which order and what parameters are exchanged in that context. E.g. calling the tespy model with the storage boundary conditions given to calculate the mass flow into storage at charging for a given power value, and then passes that to the storage model to update pressure and temperature (this process might be iterative). The proceed to the next timestep.

Maybe line out what your research/application here is really about, meaning what you want to achieve with the modeling. Otherwise I feel I cannot be of too much help other than giving you this abstract idea.

Best

Francesco

[cavemoa]

Thanks Francesco for the quick feedback.

I am starting to look into the use of onshore high pressure gas wells and their potential to be converted to small scale (5 - 20MW) CAS energy storage. The working concept is to try to utilize higher pressures than conventional CAS (>300bar), with the air stored within the steel casings of the wells, rather than in salt caverns or porous media as per your paper.

So I was initially trying to create a TESPy model/simulation (to better understand tespy) similar to that shown in your paper. With multi-stage (2 or 3?) compression and explore the impact of different lower and upper storage pressures. Evaluate a range of mass flows in , look at the power required, evaluate air temperature after each stage, calculate pressure and thermal exergy as it increases in the storage vessel.

The initial goal is to investigate the optimum max-min storage pressures range for the types of wells available for for use, by maximizing pressure exergy while probably accepting some amount of heat loss from the air stored in the wells. I have quite a range of usable max pressure vs storage volume cases to look at, as the wells exist already often with very different configurations.

Regards
Jonathan